This study tests a medicine called KT-621 for people with moderate to severe eosinophilic asthma. Asthma is a lung disease that makes it hard to breathe. This study is for people whose asthma isn't controlled well even with current medicine. Eosinophilic asthma means there are high levels of eosinophils, a type of white blood cell, in your body that can make asthma worse.

To join, you need to be between 18 and 75 years old and have been diagnosed with asthma for at least a year. You should be taking certain asthma medicines regularly and have had at least one serious asthma attack in the past year. You can't join if you have other lung diseases or are currently pregnant.

• This study will check the safety and effectiveness of KT-621.
• You will need to visit the doctor several times and complete some tests and questionnaires.
• Make sure you can attend all the study visits and follow the study rules.